W dniu 10.11.2010 21:42, Thomas Gleixner pisze:> On Wed, 10 Nov 2010, Maciej Szmigiero wrote:>> W dniu 10.11.2010 10:49, Thomas Gleixner pisze:>>> Maybe because it open codes a sloppy refcounting with a loop and magic>>> sleeps instead of converting the code to kobjects and proper>>> refcounting ?>>>>>>> The only way to do GPIO chip removal in the current code is to busy-loop.>> "Sloppy" (as you called it) waiting is still more CPU-friendly than looping >> in hope that somebody will finally release the chip.>> If you would like to implement it as kobject then go ahead and post the code>> so it can be used in drivers.> > Wait a moment. You are getting something backwards here.> > Fact is that the current code is not designed for easy hotunplugging> and therefor requires looping.> > So _you_ propose a work-around to replace the busy-loop by a sleeping> loop with "hope that ....". Hope is the least thing what counts in> programming.> > Now a reviewer tells you that your idea of replacing the busy-loop by> a sleeping in hope loop is flawed, because it does not solve the> underlying design problem of the GPIO code. And you get a suggestion> how to solve it correctly.> > Now you go and request from that reviewer to implement that? That's> not how it works.> > You sent a flawed patch in the first place and people try to tell you> how to do it right. Then it's on you to either go and do it right or> at least ask politely for help and pointers.> > Thanks,> > tglx>

You misunderstood me.By "looping in hope that somebody will finally release the chip" I meant the onlyreal way to handle a GPIO chip unplugging in the current kernel.Which is way worse that preventing new requests, then waiting for existing one to be released.And this is exactly what my patch does.

I understand that it could be simplified by removing redundant code (as Grant Likely had suggested before), andmoving it to completion interface instead of manipulating a task structure directly, but this doesn't meanthat the whole GPIO code has to be rewritten just to add one functionality.